System and method of providing compression technique for jitter sensitive application through multiple network links

ABSTRACT

An appliance for providing compression technique for jitter sensitive application through multiple network links is described. The appliance has one or more processors and includes a link quality estimator, a jitterless compressor, and a link switcher. The link quality estimator is configured to measure latency over a first link and a second link, wherein the second link has a longer latency than the first link. The jitterless compressor is configured to accumulate packets for a time period associated with a difference in latency between the second link and the first link, and determine a number of packets based on a packet size associated with the accumulated packets and bandwidth of the first link. The link switcher is configured to acquire the determined number of packets, wherein the determined number of packets have been compressed, transmit a first packet over the second link, and transmit the acquired number of packets over the first link.

BACKGROUND

A middlebox is a network appliance that manipulates Internet traffic byoptimizing data flow across the network. Middleboxes can be configuredas wide area network (WAN) optimizers and can be deployed in pairsacross two geographically separated locations to optimize data trafficbetween the two middleboxes. Middleboxes that perform WAN optimizationand virtualization work as a pair of device across two geographicallyseparated offices connected via multiple links of different WANnetworks. A middlebox (e.g., an appliance) can tunnel packets acrossmultiple links to other middleboxes to aggregate bandwidth and also toprovide compression benefits. To provide compression benefits, packetsare held in one appliance, with the data part of the packet beingaccumulated and compressed via normal compression techniques or throughdata duplication, and the compressed data being sent on the other sideappliance.

For jitter sensitive applications (e.g., real-time service applications,streaming service applications, or video clip applications), it isdifficult to provide compression benefits. For example, to providecompression, an appliance accumulates packets for compression, whichcould forcefully induce jitter into the connection. Since packet flowhas to be paused for a certain amount of time to accumulate packets forthe compression, jitter could be induced into the connection. This candrastically affect performance of the connection, especially forjitter-sensitive applications that are designed against packet jitter.Hence, these jitter sensitive applications are generally not compressedfor performance reason.

SUMMARY

In some aspects, an appliance has one or more processors and includes alink quality estimator, a link quality estimator, and a link switcher.The link quality estimator is configured to measure latency over a firstlink and a second link, wherein the second link has a longer latencythan the first link. The jitterless compressor is configured toaccumulate packets for an entire time period or a portion of the entiretime period associated with a difference in latency between the secondlink and the first link, and to determine a number of packets based on apacket size associated with the accumulated packets and bandwidth of thefirst link. The link switcher is configured to acquire the determinednumber of packets, wherein the determined number of packets have beencompressed, transmit a first packet over the second link, and transmitthe acquired number of packets over the first link.

In another aspect, a method of providing compression technique forjitter sensitive application is described. The method can includemeasuring latency over a first link and a second link, wherein thesecond link has a longer latency than the first link, accumulatingpackets for an entire time period or a portion of the entire time periodassociated with a difference in latency between the second link and thefirst link, determining a number of packets based on a packet sizeassociated with the accumulated packets and bandwidth of the first link,acquiring the determined number of packets, wherein the determinednumber of packets have been compressed, transmitting a first packet overthe second link, and transmitting the acquired number of packets overthe first link.

In yet another aspect, non-transitory computer readable storage mediumis described. The storage medium stores a set of instructions that areexecutable by at least one processor of an appliance to cause theappliance to perform a method of providing compression technique forjitter sensitive application. The method can include measuring latencyover a first link and a second link, wherein the second link has alonger latency than the first link, accumulating packets for a timeperiod associated with a difference in latency between the second linkand the first link, determining a number of packets based on a packetsize associated with the accumulated packets and bandwidth of the firstlink, acquiring the determined number of packets, wherein the determinednumber of packets have been compressed, transmitting a first packet overthe second link, and transmitting the acquired number of packets overthe first link.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference will now be made to the accompanying drawings showing exampleembodiments of this disclosure. In the drawings:

FIG. 1 is a block diagram of an exemplary network environment,consistent with embodiments of the present disclosure.

FIGS. 2A-2B are block diagrams of an exemplary computing device,consistent with embodiments of the present disclosure.

FIG. 3 is a block diagram of an exemplary appliance illustrated in FIG.1, consistent with embodiments of the present disclosure.

FIG. 4 is a block diagram of an exemplary embodiment of determining anumber of packets to be transmitted over a second link based on a packetsize associated with accumulated packets and bandwidth of a first link,consistent with embodiments of the present disclosure.

FIG. 5 is a block diagram of an exemplary embodiment of transmitting afirst packet over a link and an acquired number of packets over anotherlink, consistent with embodiments of the present disclosure.

FIG. 6 is a block diagram of an exemplary embodiment of determining andtransmitting a plurality of determined packets over one or another link,consistent with embodiments of the present disclosure.

FIG. 7 is a block diagram of an exemplary method of providingcompression technique through multiple network links, consistent withembodiments of the present disclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to the exemplary embodimentsimplemented according to the present disclosure, the examples of whichare illustrated in the accompanying drawings. Wherever possible, thesame reference numbers will be used throughout the drawings to refer tothe same or like parts.

The embodiments described herein provide appliances and methods toachieve compression benefits for jitter sensitive applications in anetwork with multiple network links by utilizing differences in theirlatency. This can be achieved by holding packets less than or equivalentto the difference in latency across multiple links to providecompression, and thus inducing no additional jitter to the connection.

FIG. 1 is a block diagram of an exemplary network environment 100. Whileexemplary network environment 100 is directed to a virtual networkenvironment, it is appreciated that the network environment can be anytype of network that communicates using packets. Network environment 100can include one or more client devices 102, a public network 104, agateway 106, an appliance 108 and/or 108′, a private network 110, a datacenter 120, and a branch office 140.

One or more client devices 102 are devices that can acquire remoteservices from data center 120 through various means. Client devices 102can communicate with a data center 120 either directly (e.g., clientdevice 102 e) or indirectly through a public network 104 (e.g., clientdevices 102 a-d) or a private network 110 (e.g., client device 102 f).When client device 102 communicates through public network 104 orprivate network 110, a communication link can be established. Forexample, a link can be established by public network 104, gateway 106,and appliance 108′, thereby providing a client device (e.g. clientdevices 102 a-d) access to data center 120. A link can also beestablished by branch office 140 including appliance 108, privatenetwork 110, and appliance 108′, thereby providing a client device (e.g.client device 102 f) access to data center 120. While client devices 102are portrayed as a computer (e.g., client devices 102 a, 102 e, and 102f), a laptop (e.g., client device 102 b), a tablet (e.g., client device102 c), and a mobile smart phone (e.g., client device 102 d), it isappreciated that client device 102 could be any type of device (e.g.,wearable or smart watch) that communicates packets to and from datacenter 120.

Public network 104 and private network 110 can be any type of networksuch as a WAN, a local area network (LAN), or a metropolitan areanetwork (MAN). As an example, a WAN can be the Internet or the WorldWide Web, and a LAN can be a corporate Intranet Public network 104 andprivate network 110 can be a wired network or a wireless network.

Gateway 106 is a physical device or is software that is part of aphysical device that interfaces between two networks having differentprotocols. Gateway 106, for example, can be a server, a router, a host,or a proxy server. In some embodiments, gateway 106 can include or becoupled to a firewall separating gateway 106 from public network 104(e.g., Internet). Gateway has the ability to modify signals receivedfrom client device 102 into signals that appliance 108′ and/or datacenter 120 can understand and vice versa.

Appliance 108 is a device that optimizes WAN traffic by including, forexample, a quality of service (“QoS”) engine. In some embodiments,appliance 108 optimizes other types of network traffic, such as LANtraffic, MAN traffic, or wireless network traffic. Appliance 108 canoptimize network traffic by, for example, scheduling data packets in anestablished communication link so that the data packets can betransmitted or dropped at a scheduled time and rate. In someembodiments, appliance 108 is a physical device, such as Citrix System'sByteMobile™, Netscaler™, or CloudBridge™. In some embodiments, appliance108 can be a virtual appliance. In some embodiments, appliance can be aphysical device having multiple instances of virtual machines (e.g.,virtual Branch Repeater).

In some embodiments, Appliances 108 can regulate or meter flow of datapackets onto WAN link. Appliances 108 can impose transparent, losslessflow control on each segment of a connection: a LAN segment between oneor more client devices 102 and appliance 108′ in data center 120, and aWAN segment between appliance 108 in branch office 140 and appliance108′ at data center 120, another LAN segment between appliance 108′ atdata center 120 and a public server (e.g., a web server). Appliances 108can independently manage flow control and utilization for each segmentindependently by splitting a connection into three segments. This isimportant when a connection's speed needs to be ramped up or down to itsfair bandwidth share and to ensure maximum advantage is taken ofenhanced WAN optimization and compression algorithms

Appliance 108 can analyze data packets. For example, appliance 108 candetermine whether an application type of the data packets is a jittersensitive application. Appliance 108 can also measure latency andbandwidth over a first link and a second link, respectively. The secondlink can have a longer latency than the first link. In order to maintainjitterless packet transfer for the connection, the first packet is sentthrough link B which has higher latency than link A. Appliance 108 canaccumulate packets for an entire time period or a portion of the entiretime period associated with a difference in latency between the secondlink and the first link. Appliance 108 can determine a number of packetsbased on a packet size associated with the accumulated packets andbandwidth of the first link. Appliance 108 can also compress thedetermined number of packets by accumulating them for a maximum time of((Packet size)/bandwidth of the first link)<latency difference betweenthe first link and the second link. Appliance 108 can transmit a firstpacket over the second link. Appliance 108 can transmit the acquirednumber of packets over the first link. After transmission, appliance 108can measure latency over the first link and the second link. Appliance108 can see the first packet over the second link and the acquirednumber of packets over the first link arrived at the other appliance108′ at the same time or almost at the same time. This induces noadditional jitter or minimum jitter on a system.

In some embodiments, a first appliance (e.g., appliance 108) works inconjunction with or cooperation with a second appliance (e.g., appliance108′) to optimize packets over multiple links. For example, the firstappliance can be located between a branch office (e.g., branch office140) and a WAN connection, while the second appliance can be locatedbetween WAN and a corporate LAN (e.g., data center 120).

In some embodiments, the functionality of gateway 106 and appliance 108′can be located in a single physical device. Appliances 108 and 108′ canbe functionally the same or similar. Moreover, in some embodiments,appliance 108′ and gateway 106 can be part of the same device. Appliance108 is further described below corresponding to FIG. 3.

Data center 120 is a central repository, either physical or virtual, forthe storage, management, and dissemination of data and informationpertaining to a particular public or private entity. Data center 120 canbe used to house computer systems and associated components, such as oneor more physical servers, virtual servers, and storage systems. Datacenter 120 can include, among other things, one or more servers (e.g.,server 122) and a backend system 130. In some embodiments data center120 can include gateway 106, appliance 108′, or a combination of both.

Server 122 is an entity represented by an IP address and can exist as asingle entity or a member of a server farm. Server 122 can be a physicalserver or a virtual server. In some embodiments, server 122 can includea hardware layer, an operating system, and a hypervisor creating ormanaging one or more virtual machines. Server 122 provides one or moreservices to an endpoint. These services include providing one or moreapplications 128 to one or more endpoints (e.g., client devices 102 a-for branch office 140). For example, applications 128 can includeMicrosoft Windows™-based applications and computing resources.

Desktop delivery controller 124 is a device that enables delivery ofservices, such as virtual desktops 126 to client devices (e.g., clientdevices 102 a-f or branch office 140). Desktop delivery controller 124provides functionality required to manage, maintain, and optimize allvirtual desktop communications.

In some embodiments, the services include providing one or more virtualdesktops 126 that can provide one or more applications 128. Virtualdesktops 126 can include hosted shared desktops allowing multiple userto access a single shared Remote Desktop Services desktop, virtualdesktop infrastructure desktops allowing each user to have their ownvirtual machine, streaming disk images, a local virtual machine,individual applications (e.g., one or more applications 128), or acombination thereof.

Backend system 130 is a single or multiple instances of computernetworking hardware, appliances, or servers in a server farm or a bankof servers and interfaces directly or indirectly with server 122. Forexample, backend system 130 can include Microsoft Active Directory™,which can provide a number of network services, including lightweightdirectory access protocol (LDAP) directory services, Kerberos-basedauthentication, domain name system (DNS) based naming and other networkinformation, and synchronization of directory updates amongst severalservers. Backend system 130 can also include, among other things, anOracle™ backend server, a SQL Server backend, and/or a dynamic hostconfiguration protocol (DHCP). Backend system 130 can provide data,services, or a combination of both to data center 120, which can thenprovide that information via varying forms to client devices 102 orbranch office 140.

Branch office 140 is part of LAN that is part of the WLAN having datacenter 120. Branch office 140 can include, among other things, appliance108 and remote backend 142. In some embodiments, appliance 108 can sitbetween branch office 140 and private network 110. As stated above,appliance 108 can work with appliance 108′. Remote backend 142 can beset up in similar manner as backend system 130 of data center 120.Client device 102 f can be located on-site to branch office 140 or canbe located remotely from branch office 140.

Appliances 108 and 108′ and gateway 106 can be deployed as or executedon any type and form of specific computing device (e.g., such as thecomputing device of FIGS. 2A-2B) capable of communicating on any typeand form of network described herein. Appliances 108 and 108′ can bedeployed individually or as a pair operatively connected together.

As shown in FIGS. 2A-2B, each computing device 200 includes a centralprocessing unit (CPU) 221 and a main memory 222. CPU 221 can be anylogic circuitry that responds to and processes instructions fetched fromthe main memory 222. CPU 221 can be a single or multiplemicroprocessors, field-programmable gate arrays (FPGAs), or digitalsignal processors (DSPs) capable of executing particular sets ofinstructions stored in a memory (e.g., main memory 222) or cache (e.g.,cache 240). The memory includes a tangible and/or non-transitorycomputer-readable medium, such as a flexible disk, a hard disk, a CD-ROM(compact disk read-only memory), MO (magneto-optical) drive, a DVD-ROM(digital versatile disk read-only memory), a DVD-RAM (digital versatiledisk random-access memory), flash drive, flash memory, registers,caches, or a semiconductor memory. Main memory 222 can be one or morememory chips capable of storing data and allowing any storage locationto be directly accessed by CPU 221. Main memory 222 can be any type ofrandom access memory (RAM), or any other available memory chip capableof operating as described herein. In the exemplary embodiment shown inFIG. 2A, CPU 221 communicates with main memory 222 via a system bus 250.Computing device 200 can also include a visual display device 224 and aninput/output (I/O) device 230 (e.g., a keyboard, mouse, or pointingdevice) connected through I/O controller 223, both of which communicatevia system bus 250. One of ordinary skill in the art would appreciatethat CPU 221 can also communicate with memory 222 and other devices inmanners other than through system bus 250, such as through serialcommunication manners or point-to-point communication manners.Furthermore, I/O device 230 can also provide storage and/or aninstallation medium for the computing device 200.

FIG. 2B depicts an embodiment of an exemplary computing device 200 inwhich CPU 221 communicates directly with main memory 222 via a memoryport 203. CPU 221 can communicate with a cache 240 via a secondary bus(not shown), sometimes referred to as a backside bus. In some otherembodiments, CPU 221 can communicate with cache 240 via system bus 250.Cache 240 typically has a faster response time than main memory 222. Insome embodiments, such as the embodiment shown in FIG. 2B, CPU 221 cancommunicate directly with I/O device 230 via an I/O port (not shown). Infurther embodiments, I/O device 230 can be a bridge 270 between systembus 250 and an external communication bus, such as a USB bus, an AppleDesktop Bus, an RS-232 serial connection, a SCSI bus, a FireWire™ bus, aFireWire 800™ bus, an Ethernet bus, an AppleTalk™ bus, a GigabitEthernet bus, an Asynchronous Transfer Mode bus, a HIPPI bus, a SuperHIPPI bus, a SerialPlus bus, a SCI/LAMP bus, a FibreChannel™ bus, or aSerial Attached small computer system interface bus, or some other typeof data bus.

As shown in FIG. 2A, computing device 200 can support any suitableinstallation device 216, such as a disk drive or other input port forreceiving one or more computer-readable media such as, for example, aUSB device, flash drive, SD memory card, a hard-drive, or any otherdevice suitable for installing software and programs such as any clientagent 220, or portion thereof. Computing device 200 can further comprisea storage device 228, such as one or more hard disk drives or redundantarrays of independent disks, for storing an operating system and otherrelated software, and for storing application software programs such asany program related to client agent 220. Optionally, any of theinstallation devices 216 could also be used as storage device 228.

Furthermore, computing device 200 can include a network interface 218 tointerface to a LAN, WAN, MAN, or the Internet through a variety of linkincluding, but not limited to, standard telephone lines, LAN or WANlinks (e.g., 802.11, T1, T3, X.25), broadband link (e.g., ISDN, FrameRelay, ATM), wireless connections (Wi-Fi, Bluetooth, Z-Wave, Zigbee), orsome combination of any or all of the above. Network interface 218 cancomprise a built-in network adapter, network interface card, PCMCIAnetwork card, card bus network adapter, wireless network adapter, USBnetwork adapter, modem or any other device suitable for interfacingcomputing device 200 to any type of network capable of communication andperforming the operations described herein.

FIG. 3 is a block diagram of an exemplary appliance 108 and/or 108′illustrated in FIG. 1, consistent with embodiments of the presentdisclosure. Appliance 108 can include one or more network interfaces218A-N consistent with network interface 218 of FIG. 2A, a packetprocessing engine 310, a QoS engine 320, a jitterless compressor 330, alink quality estimator 340, a link switcher 350, a policy engine 360,and a cache manager 370. Although FIG. 3 depicts network interfaces218A-218N as two network interfaces, it is appreciated that interfaces218A-218N can include any number of network interfaces.

Packet processing engine 310, which is also referred to as a “packetengine,” a “packet processor,” or a “data processor,” is responsible forcontrolling and managing the processing of data packets received andtransmitted by appliance 108 via network interfaces 218A-N. Packetprocessing engine 310 can be one or more modules, which can be one ormore packaged functional hardware units designed for use with othercomponents or a part of a program that performs a particular function(e.g., controlling and managing the processing of data packets),corresponding to the particular step of related functions. Packetprocessing engine 310 can be embodied as a single packet engine or anynumber of a plurality of packet engines that can operate at data linklayer (layer 2), network layer (layer 3), or transport layer (layer 4)of a network protocol stack (e.g., such as the layers and protocols ofthe Open System Interconnection communications model). Packet processingengine 310 can be configured to accomplish some or all of the stepsdescribed herein after being executed by CPU 221 and/or QoS engine 320.In some aspects, the data packets can be carried over the data linklayer via the Ethernet communication protocol, which can comprise any ofthe family of WAN or LAN protocols, such as those protocols covered bythe IEEE 802.3. In other aspects, the network stack can have any typeand form of wireless protocols, such as IEEE 802.11 and/or mobileinternet protocols. In some embodiments, packet processing engine 310intercepts or receives data packets at the network layer, such as viathe IP communication protocol. In some embodiments, packet processingengine 310 can intercept or receive data packets at the transport layer,such as via the TCP communication protocols. Packet processing engine310 can operate at any session or any application layer above thetransport layer.

Packet processing engine 310 can include a buffer for queuing one ormore data packets during processing of the data packets. Additionally,packet processing engine 310 can communicate via one or morecommunication protocols to transmit and receive a plurality of networkdata packets across one or more links via network interfaces 218A-N. Thelinks can connect appliance 108 to appliance 108′. Packet processingengine 310 can be configured to acquire data regarding the flow andstore, the acquired data in an operatively connected computer memory(e.g., compression history database). The sent and received data packetsoperating across one or more links can be considered “data flows” or“flows.” In some embodiments, packet processing engine 310 can sendpackets or header information of the packets to QoS engine 320 torequest QoS engine 320 to determine QoS characteristics of the packets,e.g., whether an application type of the packets is a jitter sensitiveapplication or not. Jitter sensitive application can be determined basedon information in the packet. For example, the packet can include atleast one of: an application type field, a jitter sensitivenessindicator, and a data characteristics field. For example, applicationtype field can include voice over IP application, video streaming, BBC,CNN, youtube, netflix, etc. Jitter sensitiveness indicator can indicatewhether the packet contains jitter sensitive data, and can have boolean(e.g., yes or no) information. Data characteristics field can indicatewhether the packet has realtime or non-realtime characteristics. Datacharacteristics field can also indicate video or audio characteristics.

During operations of appliance 108, packet processing engine 310 caninterface, be integrated with, or be in communication with any portionof appliance 108, such as QoS engine 320, jitterless compressor 330,link quality estimator 340, link switcher 350, policy engine 360, and/orcache manager 370. As such, any of the logic, functions, or operationsof QoS engine 320, jitterless compressor 330, link quality estimator340, link switcher 350, policy engine 360, and/or cache manager 370 canbe performed in conjunction with or in responsive to packet processingengine 310. Packet processing engine 310 can be controlled by and/orexecute any operation described herein.

QoS engine 320, which is also referred to as a “QoS controller,” or a“QoS packet scheduler,” can perform one or more QoS optimizationtechniques for jitter sensitive applications, etc. QoS engine 320 can beone or more modules, which can be one or more packaged functionalsoftware and/or hardware units designed for use with other components ora part of a program that performs a particular function (e.g.,optimization techniques), corresponding to the particular step ofrelated functions. QoS engine 320 can be configured to improve theperformance, operation, or quality of service of any type of networktraffic. QoS engine 320 performs these techniques, for example, by usingdefined logic, business rules, functions, or operations. In someembodiments, QoS engine 320 can perform network traffic optimization andmanagement mechanisms that provide different priorities to differentusers, applications, flows, or links. QoS engine 320 can also control,maintain, or assure a certain level of performance to a user,application, flow, or connection. When receiving packets or headerinformation of the packets from packet processing engine 310, QoS engine320 can determine whether an application type of the packets is a jittersensitive application or not and send such determined information tojitterless compressor 330. QoS engine 320 can direct link qualityestimator 340 to perform any or all steps for determining one or morelink quality. For example, QoS engine 320 can control, maintain,prioritize and/or assure a certain portion of bandwidth or networkcapacity of a communication link for a user, application, one or moreflows, or links, collect data in connection with one or more flows andlinks, analyze the collected data, allocate or instruct to allocateoptimal bandwidth over certain network link. QoS engine 320 can observetraffic behaviors and user behaviors, and based on the traffic and userbehaviors, determine relative allocation of bandwidth over networklinks.

In some embodiments, QoS engine 320 can monitor the achieved level ofperformance or the quality of service (e.g., the data rate, delay,dropped packets, etc.) corresponding to a user, application, flow,and/or link, and then dynamically control or adjust one or more packetcharacteristics in connection with sending and receiving data packets toachieve a desired level of performance or quality of service. QoS engine320 can coordinate the acquisition and delivery of packetcharacteristics with packet processing engine 310. QoS engine 320 canalso coordinate the acquisition and delivery of link characteristicsbetween components of appliance 108, for example, between packetprocessing engine 310, jitterless compressor 330, and link qualityestimator 340. QoS engine 320 can direct link quality estimator 340 toperform some or all of the steps according to exemplary embodimentsdisclosed herein. For example, QoS engine 320 can determine whether anapplication type of the packets is a jitter sensitive application. QoSengine 320 can determine jitter sensitive application based oninformation in the packet. For example, the packet can include at leastone of: an application type field, a jitter sensitiveness indicator, anda data characteristics field. For example, application type field caninclude voice over IP application, video streaming, etc. Jittersensitiveness can be determined by QoS engine 320 based on theapplication. Data characteristics field can indicate whether the packethas realtime or non-realtime characteristics. Data characteristics fieldcan also indicate video or audio characteristics. QoS engine 320 canprovide jitterless compressor 330 with the information that theapplication type of packets is a jitter sensitive application.

Jitterless compressor 330 can include any logic, rules, functions, oroperations for determining a number of packets to be transmitted over alink based on a packet size associated with accumulated packets andbandwidth of another link, or any other function or operation performedby appliance 108. Jitterless compressor 330 can include a buffer forqueuing one or more data packets during processing of the data packets.Jitterless compressor 330 can receive packets from packet processingengine 310 or QoS engine 320. Jitterless compressor 330 can also receiveapplication type information of packets from QoS engine 320. Jitterlesscompressor 330 can receive link quality information from link qualityestimator 340 such as minimum latency, currently measured latency, andbandwidth over each network link, for example, between two appliances108 and 108′. Based on inputs from QoS engine 320 and link qualityestimator 340, jitterless compressor 330 can determine which packetshave to be sent through one or more selected links. In particular,jitterless compressor 330 can determine which train of packets is to besent through a low latency link or a higher latency link.

Assuming that there are packets to be transmitted from an appliance 108to another appliance 108′, there are two links chosen between the twoappliances 108 and 108′, jitterless compressor 330 can send (or providean instruction to send) a first packet over a link (e.g., a second link)with higher latency than another link (e.g., a first link). Jitterlesscompressor 330 can also be configured to accumulate packets for anentire time period or a portion of the entire time period associatedwith a difference in latency between the second link and the first link.In some embodiments, jitterless compressor 330 can be configured todetermine an optimal time period associated with a difference in latencybetween the second link and the first link for coordinating the sendingof the first packet over the second link and of an acquired number ofpackets over the first link so that the first packet and the acquirednumber of packets arrive at the same time or almost at the same time.

For example, in the scenario where the latency and bandwidth on thefirst link is T1 and B1, respectively, and the latency and bandwidth onthe second link is T2 and B2, respectively, it is assumed that thelatency of T2 is greater than T1. To maintain jitterless packet transferfor the connection, the first packet is sent through the second link,which has a higher latency than the first link. Jitterless compressor330 can compress the subsequent designated packets by accumulating thembased on a maximum time of ((Packet size)/B1)<(T2-T1). In other words,jitterless compressor 330 can accumulate packets for a time period ofthe latency difference between the two links, and thus it is ensuredthat the packets arrive in appliance 108′ on both links at the same timeor almost at the same time. After accumulating the packets on the firstlink and for the time ((Packet size)/B1)<(T2-T1), the next packet issent on the second link and the process continues.

Jitterless compressor 330 can be configured to determine a number ofpackets based on a packet size associated with the accumulated packetsand bandwidth of the first link. Using the determination above, assumingthat T1=60 ms, B1=10 Mbps, T2=100 ms, B2=15 Mbps, and the average packetsize is 1500 bytes, jitterless compressor 330 can determine a number ofpackets to be transmitted over the first link (N) based on the followingdetermination:(Packet size)/B1<(T2−T1),(N*1500*8)/10*10⁶<(100 ms−60 ms),(N*1500*8)/10*10⁶=80% of 40 ms,N*12*10⁻⁴=320*10⁻⁴N=320/12=26 packetsIn the above example, it is appreciated that 80% of the difference inlatency is taken into account for any differences/errors in transmissiondelay. It is also possible to apply other percentages as the differencein latency based on various factors. Factors can include for example,radio or link condition, network congestion status, available bandwidth,round trip time, etc. Depending on a determined percentage of thedifference in latency, a first packet over a link and any one ofsubsequent packets (e.g., 26 packets from the above example) overanother link can arrive at the other appliance 108′ at the same time oralmost at the same time. The key is to minimize the gap of arrival timeof the first packet over a link and any one of subsequent packets overanother link.

Jitterless compressor 330 can determine when to perform determination ofa number of packets to be transmitted on a link. In some embodiments,jitterless compressor 330 can determine a number of packets to betransmitted on a link each round. From the example above, the number ofpackets is determined, N=26. After transmitting 26 packets on the firstlink, jitterless compressor 330 can determine another number of packetsto be transmitted on the first link. In other embodiments, jitterlesscompressor 330 can reuse a previously determined number of packets forcertain rounds. This can be because there can be no much change on radioor link condition or round trip time, for example. For instance, whentransmitting a large size of data such as a video clip, it can bepacketized into a plurality of packets (e.g., 200 packets). From theexample above, the number of packets is determined, N=26. Jitterlesscompressor 330 can transmit the first packet, which can be noted aspacket #1, on the second link and transmit packet #2-#27 on the firstlink. Jitterless compressor 330 can determine reusing the determinednumber of packets. After transmitting packet #2-#27 on the first link,jitterless compressor 330 can transmit packet #28 on the second link andpacket #29-#54 on the first link, and can repeat this process.

Jitterless compressor 330 can compress the determined number of packets,such as 26 packets in the above example with 80% of the difference inlatency. Jitterless compressor 330 can instruct link switcher 350 totransmit the compressed packets over the first link.

Link quality estimator 340 can include any logic, rules, functions, oroperations for measuring and providing latency and bandwidth over alink, or any other function or operation performed by appliance 108.Link quality estimator 340 can identify a number of network links. Linkquality estimator 340 can also choose a link among a number of networklinks to transmit one or more packets. Link quality estimator 340 canmeasure latency over each link. Link quality estimator 340 can measureminimum latency over each link or overall links. Link quality estimator340 can measure bandwidth of each link. Link quality estimator 340 canprovide measured minimum latency and current latency information on eachlink, and bandwidth information on each link with jitterless compressor330. In some embodiments, link quality estimator 340 receives andadjusts into a new bandwidth on a link after receiving bandwidthre-allocation instructions on the link from QoS engine 320.

Link switcher 350 can include any logic, rules, functions, or operationsfor determining a network link and providing transmission of one morepackets, or any other function or operation performed by appliance 108.Link switcher 350 can acquire, from jitterless compressor 330, thedetermined number of packets that have been compressed. Link switcher350 can also receive instructions from jitterless compressor 330 overwhich link the determined number of packets are to be transmitted. Usingthose instructions, link switcher 350 can transmit a first packet overthe link that has higher latency than the other link. Link switcher 350can transmit the acquired number of packets over the first link, such asthe 26 packets in the above example with 80% of the difference inlatency. In some embodiment, link switcher 350 can transmit a nextpacket over the second link, after transmitting the acquired number ofpackets over the first link. Link switcher 350 can transmit the nextpredetermined number of packets that have been compressed over the firstlink.

Appliance 108 can also include a policy engine 360, also referred to asa policy controller or a policy provider. Policy engine 360 can be oneor more modules and can include any logic, function, or operations forproviding and applying one or more policies or rules to the function,operation, or configuration of any portion of the appliance 108. In someembodiments, policy engine 360 provides a configuration mechanism toallow a user to identify, specify, define, or configure a policy forappliance 108, or any portion thereof. For example, policy engine 360can provide a predefined traffic optimization configuration policyincluding the number of priorities, the priorities associated with eachservice class, the number of connections allowed under each serviceclass, link bandwidth configuration, and any other policy information.Policy engine 360 can also provide policies for what data to cache, whento cache the data, for whom to cache the data, when to expire an objectin cache, or when to refresh the cache. Policy engine 360 can alsoinclude any logic, rules, functions, or operations for determining andproviding access, control, and management of data packets received andstored by packet processing engine 310. Policy engine 360 can alsoinclude any logic, rules, functions, or operations for determining andproviding access, control and management of security, network traffic,network access, compression, or any other function or operationperformed by appliance 108.

Cache manager 370 is one or more modules configured to store data,information, and objects to a cache in memory or storage, to providecache access, and to control and manage the cache. The data, objects, orcontent processed and stored by cache manager 370 can include data inany format, such as a six-byte MAC address, a data packet, or any typeof data communicated via any communication protocol. Examples of typesof data can include, for example, one or more priority information ofdata in any incoming connection request. Examples of types of data canalso include, for example, one or more priority information of aconnection conveying data. Examples of types of data can also include,for example, one or more packet characteristics including information inconnection with packet loss rates, queuing delays, flow congestion,sizes of congestion windows, minimum latency, measured latency of one ormore links, bandwidth of one or more links, average round trip times,etc. Cache manager 370 can save data and/or a link pointing to a storedlocation of the data in a fast-access cache memory, such as cache 240.In some embodiments, cache manager 370 can duplicate original datastored in a slow-access storage and store the data in a fast-accesscache memory, such as cache 240. After the data is stored in the cache,future use can be made by accessing the cached copy rather thanrefetching or recomputing the original data, thereby reducing the accesstime. In some embodiments, the cache can comprise a data object inmemory of appliance 108. In some embodiments, the cache can comprise anytype and form of storage element of appliance 108, such as a portion ofa hard disk. In some embodiments, as described above, the processingunit of the device, such as CPU 221, can provide cache memory for use bycache manager 350. Cache manager 370 can use any portion and combinationof main memory 222, storage 228, or CPU 221 for caching data, objects,and other content. Cache manager 370 can comprise any type of generalpurpose processor (GPP), or any other type of integrated circuit, suchas a Field Programmable Gate Array (FPGA), Programmable Logic Device(PLD), or Application Specific Integrated Circuit (ASIC).

FIG. 4 is a block diagram of an exemplary embodiment of determining anumber of packets to be transmitted over a second link based on a packetsize associated with accumulated packets and bandwidth of a first link,consistent with embodiments of the present disclosure.

Packet processing engine 310 can send packets or header information ofthe packets to QoS engine 320 to request that QoS engine 320 determineQoS characteristics of the packets, e.g., whether an application type ofthe packets is a jitter sensitive application or not. When QoS engine320 determines that the application type of the packets is a jittersensitive application, QoS engine 320 can provide the application-typeinformation to jitterless compressor 330. Link quality estimator 340 canmeasure minimum latency, current latency over each link, and bandwidthover each link and provide the measured information to jitterlesscompressor 330.

Based on the received information from QoS engine 320 and link qualityestimator 340, jitterless compressor 330 can determine a number ofpackets to be transmitted over a link based on a packet size associatedwith the accumulated packets and bandwidth of another link. Assumingthat there are packets to be transmitted from an appliance 108 toanother appliance 108′ and that there are two links chosen between thetwo appliances 108 and 108′, jitterless compressor 330 can send a firstpacket over a link (e.g., link B, 510) with higher latency than anotherlink (e.g., link A, 520). Jitterless compressor 330 can also beconfigured to accumulate packets for an entire time period or a portionof the entire time period associated with a difference in latencybetween link A and link B. Jitterless compressor 330 can be configuredto determine an optimal time period associated with a difference inlatency between link A and link B in order to make the first packet overlink B and an acquired number of packets over link A arrived at the sametime or almost at the same time. For example, let latency and bandwidthon link A be T1 and B1 and for link B be T2 and B2, respectively. Letthe latency T2>T1. In order to maintain jitterless packet transfer forthe connection, the first packet is sent through link B, which hashigher latency than link A. Then, jitterless compressor 330 can compressthe packets by accumulating them for a maximum time of ((Packetsize)/B1)<(T2−T1). In other words, jitterless compressor 330 canaccumulate packets for a time period of the latency difference betweenthe two links (e.g., link A and link B), allowing appliance to send thecompressed packets so that the first packet and the compressed packetsarrive in appliance 108′ on both links at the same time or almost at thesame time. Since the compressed packets are sent on a second link (e.g.,link A) with a time difference of (T2−T1), the first packet and thecompressed packets can arrive in appliance 108′ at the same time oralmost at the same time. Jitterless compressor 330 can repeat thisprocess by accumulating packets for the time ((Packet size)/B1)<(T2−T1),and providing instructions to link switcher 350 to transmit a next firstpacket on link B and compressed subsequent packets on link A. Inexemplary embodiments, assuming that latency and bandwidth on link A beT1=60 ms and B1=10 Mbps and for link B be T2=100 ms and B2=15 Mbps,average packet size be 1500 bytes, and 80% of the difference in latencyfor transmission delay, jitterless compressor 330 can determine 26packets to be transmitted over link A. Although 80% of the difference inlatency is taken into account for transmission delay in this assumption,it is also possible to apply other percentages as the difference inlatency based on various factors. Factors can include for example, linkcondition, network congestion status, available bandwidth, round triptime, etc. Depending on a determined percentage of the difference inlatency, the first packet over a link and any one of subsequent packetsover another link can arrive at the other appliance 108′ at the sametime or almost at the same time. The key is to minimize the gap ofarrival time of the first packet over a link and any one of subsequentpackets over another link. Jitterless compressor 330 can compress thedetermined number of packets and can instruct link switcher 350 totransmit the compressed packets over link A.

FIG. 5 is a block diagram of an exemplary embodiment of transmitting afirst packet over a link and an acquired number of packets over anotherlink, consistent with embodiments of the present disclosure. As anexample, FIG. 5 shows that there are a plurality of packets (e.g., nnumber of packets) to be transmitted over two links between appliance108 and appliance 108′. The two links include link A 520 and link B 510.Link B 510 (e.g., 100 ms latency) has a longer latency than link A 520(e.g., 60 ms latency). Although FIG. 5 shows two links between theappliances 108 and 108′, it is also possible that more than two linkscan be used to transmit a plurality of packets between them to make theplurality of packets arrived at appliance 108′ at the same time oralmost at the same time.

Appliance 108 can send a first packet over link B 510 having a longerlatency than link A 520. Appliance 108 can accumulate packets for anentire time period or a portion of the entire time period of the latencydifference between the two links, and thus it is ensured that thepackets arrive in appliance 108′ on both links at the same time oralmost at the same time. Appliance 108 can determine a number of packets(e.g., (n−1) number of packets as exampled in FIG. 5) based on a packetsize associated with the accumulated packets and bandwidth of link A520. Appliance 108 can compress the determined number of packets andtransmit the compressed packets over link A 520. Then, the first packetand the compressed (n−1) number of packets arrive at appliance 108′ atthe same time or almost at the same time and this thus induces noadditional jitter or minimum jitter. Packets can arrive out of order atappliance 108′. Appliance 108′ can re-order received packets based onsequence number of each packet. Upon receipt of the compressed (n−1)number of packets, appliance 108′ can decompress, re-order, and send thepackets to the other end (e.g., a public server).

FIG. 6 is a block diagram of an exemplary embodiment of determining andtransmitting a plurality of determined packets over one or another link,consistent with embodiments of the present disclosure. FIG. 6 shows aplurality of packets (e.g., (2n+1) number of packets) to be transmittedover the two links, e.g., link B 510 and link A 520. As described abovein FIG. 5, the first packet is transmitted over link B 510, and (n−1)number of packets (e.g., packet 2˜packet n) is determined based on apacket size associated with the accumulated packets and bandwidth oflink A 520. Packet 2-packet n are compressed and transmitted over link A520. After accumulating packets on link A 520 and for the time ((Packetsize)/bandwidth of link A<latency difference between link A and link B),the next packet, packet n+1, is transmitted over link B 510. Packetn+2˜packet 2 n are compressed and transmitted over link A 520. Afteraccumulating packets on link A 520 and for the time ((Packetsize)/bandwidth of link A)<latency difference between link A and link B,the next packet, packet 2n+1, is transmitted over link B 510. Thelatency is re-computed and this operation runs continuously.

For example, assuming that latency and bandwidth on link A 520 be T1=60ms and B1=10 Mbps and for link B be T2=100 ms and B2=15 Mbps, averagepacket size be 1500 bytes, and 80% of the difference in latency fortransmission delay, it is determined that 26 packets are to betransmitted over link A 520 and thus n becomes 27. Packet 1 istransmitted over link B 510 and 26 packets which are packet 2-packet 27are compressed and transmitted over link A 520. Then, packet 28 istransmitted over link B 510 and 26 packets which are packet 29˜packet 54are compressed and transmitted over link A 520. The latency isre-computed and this operation runs continuously.

FIG. 7 is a block diagram of an exemplary method of providingcompression technique through multiple network links, consistent withembodiments of the present disclosure. It will be readily appreciatedthat the illustrated procedure can be altered to change one or moresteps in order, delete steps or further include additional steps. Whilemethod 700 is described as being performed by an appliance (e.g.,appliance 108), it is appreciated that method 700 can be performed byother devices alone or in combination with the appliance.

As an initial step 710, appliance 108 can measure latency over a firstlink and a second link. The second link can have a longer latency thanthe first link. For example, the second link can have 100 ms latency andthe first link can have 60 ms latency. At step 720, appliance 108 canaccumulate packets for an entire time period or a portion of the entiretime period associated with a difference in latency between the secondlink and the first link. This is to achieve no additional jitter orminimum jitter by making a first packet over the second link and anumber of packets over the first link arrived in the other appliance108′ at the same time or almost at the same time.

At step 730, appliance 108 can determine a number of packets based on apacket size associated with the accumulated packets and bandwidth of thefirst link. For example, assuming that bandwidth on the first link be 10Mbps, average packet size of the accumulated packets are 1500 bytes, and80% of the difference in latency for transmission delay, appliance 108can determine 26 packets to be transmitted over the first link based onthe following calculation:(N*1500*8)/10*10⁶=80%*(100 ms−60 ms),N=26.

At step 740, appliance 108 can obtain the determined number of packets,which can be compressed. In the above-example at step 730, appliance 108obtains and compresses 26 packets to be transmitted over the first link.

Appliance 108 can transmit a first packet over the second link at step750 and transmit the acquired number of packets over the first link atstep 760. In the above-example at step 730, appliance 108 transmits the26 packets that have been compressed over the first link. Aftertransmission, appliance 108 can measure latency over the first link andthe second link. Appliance 108 can send the first packet over the secondlink and the acquired number of packets over the first link so that theyarrive at the other appliance 108′ at the same time or almost at thesame time. This induces no additional jitter or minimum jitter on asystem. The methods in FIG. 7 can be run continuously until no morepackets are accumulated at appliance 108.

In the foregoing specification, embodiments have been described withreference to numerous specific details that can vary from implementationto implementation. Certain adaptations and modifications of thedescribed embodiments can be made. Other embodiments can be apparent tothose skilled in the art from consideration of the specification andpractice of the embodiments disclosed herein. It is intended that thespecification and examples be considered as exemplary only. It is alsointended that the sequence of steps shown in figures are only forillustrative purposes and are not intended to be limited to anyparticular sequence of steps. As such, those skilled in the art canappreciate that these steps can be performed in a different order whileimplementing the same method.

What is claimed is:
 1. An appliance having one or more processors andcomprising: a link quality estimator configured to measure latency overa first link and a second link, wherein the second link has a longerlatency than the first link; a jitterless compressor configured to:accumulate packets for a time period associated with a difference inlatency between the second link and the first link; determine a numberof packets based on a packet size associated with the accumulatedpackets and bandwidth of the first link; a link switcher configured to:acquire the determined number of packets, wherein the determined numberof packets have been compressed; transmit a first packet over the secondlink; and transmit the acquired number of packets over the first link.2. The appliance of claim 1, wherein the link quality estimator isfurther configured to measure link quality, wherein the link qualityincludes bandwidth over each link.
 3. The appliance of claim 1, whereinthe link quality estimator is further configured to measure minimumlatency over the first link and the second link.
 4. The appliance ofclaim 1, wherein the jitterless compressor is further configured todetermine an optimal time period associated with a difference in latencybetween the second link and the first link in order to make the firstpacket over the second link and the acquired number of packets over thefirst link arrived at the same time.
 5. The appliance of claim 1,wherein the link switcher is further configured to transmit a nextpacket over the second link, after transmitting the acquired number ofpackets over the first link.
 6. The appliance of claim 5, wherein thelink switcher is further configured to transmit next packets in a unitof the determined number of packets over the first link.
 7. Theappliance of claim 1, further comprises a quality of service engineconfigured to determine whether an application type of the packets is ajitter sensitive application.
 8. A method of providing compressiontechnique for jitter sensitive application, the method comprising:measuring latency over a first link and a second link, wherein thesecond link has a longer latency than the first link; accumulatingpackets for a time period associated with a difference in latencybetween the second link and the first link; determining a number ofpackets based on a packet size associated with the accumulated packetsand bandwidth of the first link; acquiring the determined number ofpackets, wherein the determined number of packets have been compressed;transmitting a first packet over the second link; and transmitting theacquired number of packets over the first link.
 9. The method of claim8, further comprising measuring link quality, wherein the link qualityincludes bandwidth over each link.
 10. The method of claim 8, furthercomprising measuring minimum latency over the first link and the secondlink.
 11. The method of claim 8, further comprising determining anoptimal time period associated with a difference in latency between thesecond link and the first link in order to make the first packet overthe second link and the acquired number of packets over the first linkarrived at the same time.
 12. The method of claim 8, further comprisingtransmitting a next packet over the second link, after transmitting theacquired number of packets over the first link.
 13. The method of claim12, further comprising transmitting next packets in a unit of thedetermined number of packets over the first link.
 14. The method ofclaim 8, further comprising determining whether an application type ofthe packets is a jitter sensitive application.
 15. A non-transitorycomputer readable storage medium that stores a set of instructions thatare executable by at least one processor of an appliance to cause theappliance to perform a method of providing compression technique forjitter sensitive application, the method comprising: measuring latencyover a first link and a second link, wherein the second link has alonger latency than the first link; accumulating packets for a timeperiod associated with a difference in latency between the second linkand the first link; determining a number of packets based on a packetsize associated with the accumulated packets and bandwidth of the firstlink acquiring the determined number of packets, wherein the determinednumber of packets have been compressed; transmitting a first packet overthe second link; and transmitting the acquired number of packets overthe first link.
 16. The non-transitory computer readable storage mediumof claim 15, the method further comprising measuring link quality,wherein the link quality includes bandwidth over each link.
 17. Thenon-transitory computer readable storage medium of claim 15, the methodfurther comprising measuring minimum latency over the first link and thesecond link.
 18. The non-transitory computer readable storage medium ofclaim 15, the method further comprising determining an optimal timeperiod associated with a difference in latency between the second linkand the first link in order to make the first packet over the secondlink and the acquired number of packets over the first link arrived atthe same time.
 19. The non-transitory computer readable storage mediumof claim 15, the method further comprising transmitting a next packetover the second link, after transmitting the acquired number of packetsover the first link.
 20. The non-transitory computer readable storagemedium of claim 19, the method further comprising transmitting nextpackets in a unit of the determined number of packets over the firstlink.